The lock devices of the above type comprise a handle, a square pin, handle return means, an engagement unit and seating unit, placed through the door shutter thickness.
The seating unit is inserted through the door shutter, in an especially made hole. The square pin is inserted through the unit, at the end thereof there are mounted the handles; the return means are seated in the unit and are engaged with the square pin; the square pin is also engaged with the engagement unit, comprising an engagement element, in the jargon called “bolt”, suitable for engaging the door shutter to the jamb thereof, for keeping the door closed.
The seating unit must meet several requirements, to make a durable lock device functional to the requirements of user and installer.
In particular, the seating unit must make a suitable support for the handles, often heavy, and must reliably absorb the actions relieved thereon for the repeated actuations of the handles.
For installation requirements, the seating unit comprises two bodies slidingly associable to one another, for adapting the unit to different dimensions of the door shutter thickness.
To make a unit sufficiently resistant to the above actions it is therefore necessary that the two component bodies thereof are strongly engaged to each other.
In known embodiments, such requirement is partly met through screws that engage the two unit bodies.
The bodies seat the elastic return means, so there are provided covers for covering the return means seating rooms. Also the covers must be strongly engaged with the bodies.
In known embodiments, such requirement is met through three screws that engage the covers to the bodies.
The above requirements create a set of structural hindrances inside the seating unit that strongly limit the available angle of rotation for the handle rotation.